1. Field of the Invention
The present invention relates to a method for marking metallic alloys using laser alloying. Specifically, the present invention is directed toward the use of laser alloying steel or aluminum alloys with a mark that provides protection against wear and corrosion and greater permanency.
2 . Description of the Prior Art
Items made of steel or aluminum have been marked for a variety of reasons including identifying one or more characteristics of the item. One method of marking employs the use of a visible marking substance, such as ink or paint. Such marking substances are subject to fading and/or wear, particularly in abrasive environmental conditions such as wind, rain, and/or direct sunlight. In many cases it is desirable to mark a component prior to the completion of the manufacturing process. It is desirable to have a mark that will not deteriorate during the manufacturing process, which may include heating, bending, abrasion machining and/or welding.
Other methods of marking involve imprinting a visible mark into the surface of an item, such as by etching, engraving, or punching. Methods such as etching or engraving result in some loss of material from the substance to be marked. Methods such as punching result in compression of material, sometimes resulting in a change in the mechanical properties of the material.
The present invention overcomes the drawbacks of the prior art by providing a method of marking steel or aluminum alloys which is far more resistant to wear, abrasion, and fading, and which does not result in a loss of material or in compression of the material to be marked.
The present invention is directed toward a method for laser marking of metallic alloys. This method comprises applying a layer of precursor comprising a binder and metallic or ceramic powder to a steel or aluminum substrate. The layer has a thickness in the range of 50-250 microns. The method further comprises irradiating the surface of the substrate with a laser beam at a sufficient energy level and for a sufficient time to produce a corrosion and/or wear resistant alloyed apron on the substrate. The laser beam used to perform this step of producing an alloyed apron is referred to herein as the xe2x80x9calloying laser beam.xe2x80x9d The irradiation is performed while the substrate and the laser beam are moved relative to each other. The method further comprises marking on the apron with the laser beam to produce a pre-selected marking on the apron. The laser beam used to perform the step of marking the apron is referred to herein as the xe2x80x9cmarking the laser beam.xe2x80x9d